Forming mill guides

ABSTRACT

Forming mill guides for use in an apparatus for forming a strip material into a tube wherein the strip thickness to tube diameter ratio is less than 3 percent. The guides are located intermediate each of the forming stands in the forming mill portion of the apparatus and prevent the edges of the strip or tube from popping out or buckling. The guides generally comprise a member having a concave face which is contoured to contact and support the strip or tube between each of the respective forming stands. The apparatus also includes means for aligning the guides with the strip or tube and is particularly applicable to the formation of non-ferrous alloy tubing, such as copper or copper base alloys. The guides are preferably formed of a plastic material, such as nylon.

United States Patent Morris FORMING MILL GUIDES [72] Inventor: Jack Morris, Orange, Conn. [73] Assignee: Olin Corporation [22] Filed: May 24, 1971 [21] Appl. No.: 146,138

[52] US. Cl. ..219/8.5, 219/59 228/44 [51] Int. Cl. ..H1)5b 5/00 [58] Field of Search ..-.2l9/8.5, 5'9, 62, 64, 67, 101,

[56] References Cited UNITED STATES PATENTS 3,585,351 6/1971 l-linrichs .(219/121 EM 2,936,357 5/1960 Crawford ..219/8.5 3,209,117 9/1965 Morris et al. ..2l9/59 3,548,141 12/1970 Remus ..219/62 1,812,409 6/1931 Leckie ..219/67 X 3,175,069 3/1965 Kohler et al ..219/59 3,431,383 3/1969 Ullery, Jr. et a]. ..2l9/59 3,558,839 1/1971 Oppermann ..219/59 X 1 Sept. 12, 1972 Primary Examiner-R. F. Staubly Assistant Examiner-L. A. Schutzman Attorney-Robert H. Bachman, Gordon G. Menzies and Paul Weinstein [5 7] ABSTRACT Forming mill guides for use in an apparatus for forming a strip material into a tube wherein the strip thickness to tube diameter ratio is less than 3 percent. The guides are located intermediate each of the forming stands in the forming mill portion of the apparatus and prevent the edges of the strip or tube from popping out or buckling. The guides generally comprise a member having a concave face which is contoured to contact and support the strip or tube between each of the respective forming stands. The apparatus also includes means for aligning the guides with the strip or tube and is particularly applicable to the formation of non-ferrous alloy tubing, such as copper or copper base alloys. The guides are preferably formed of a plastic material, such, as nylon.

13 Claims, 9 Drawing Figures PATENTEB SEP 1 2 I972 sum 2 0F 5 FIG-2 FIG-7 INVENTOR w W M m M ATTORNEY PATENTED 2 9 2 3.691. 337' sum 3 OF 5 JACK MORRIS INVENTOR A Fl URN! Y PATENTEUsEP 1 21912 SHEET 0F 5 P ll/ PRIOR AR T JACK MORRIS NVENTOR ATTORN EY PATENTEU I 3.691. 337

sum 5 0F 5 JACK MORRIS INVENTOR ATTORNEY FORMING MILL GUIDES BACKGROUND OF THE INVENTION This invention relates to an apparatus forforming strip into tubing. It is particularly useful with apparatus employing high frequency welding techniques.

' When forming a strip of material into the shape of a tube, the edges tend to elongate. A forming mill used to shape the strip generally includes a plurality of roll stands or dies. As the strip progressively travels through the mill from one roll stand to the next, the elongation in the edges progressively accumulates. When the strip thickness to diameter ratio is less than 3 percent and particularly when it is less than 2 percent; especially for large diameters on the order of 3 inches or more, the strip has no column strength to maintain its shape against spring back. Consequently on progressing from stand to stand, the strip tends to pop out or buckling of the edges occurs. These effects occur even though side enclosure rolls are used to support the edges between the respective roll stands.

I SUMMARY OF THE INVENTION In accordance with this invention, the problem of edge pop out and/or buckling has been substantially eliminated by the use of guides in place of side enclosure rolls. The guides extend over a substantial portion of the distance between each of the forming stands in the forming mill section of the tube mill.

The guides have a face which is contoured to contain and support the strip between respective forming stands. The guides are adjustable and support the edges in a continuous transition from both up stream and down stream forming stands.

The guides are normally formed of a material such as nylon although numerous other materials may be employed as will be discussed hereinafter.

It is accordingly an object of this invention to provide means for containing and supporting the strip edges between forming stands when forming a strip of material into the shape of a tube.

It is another object of this invention to provide means as above wherein the face which contains the strip material follows the continuous transition of the strip surface from both the up stream and down stream forming roll stands.

It is a further object of this invention to provide means as above in the shape of guides formed of a material such as nylon or the like. 7

Other objects and advantages will become apparent to those skilled in the art as a detailed description of the preferred embodiments proceeds with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a flow diagram for a typical apparatus for forming strip material into tubing.

FIG. 2 shows typical cross sections of the strip and partially formed tube at each of the forming stands in the forming mill superimposed upon one another.

FIG. 3 shows a perspective view of a preferred joining apparatus for use in accordance with this invention.

FIG. 4 shows a top view of a portion of a forming mill typical of the prior art.

FIG. 5 shows a top view of a portion of a forming mill having guide means in accordance with this invention.

FIG. 6 shows a perspective view illustrating the engagement between the guide means in accordance with this invention and the preformed tube.

FIG. 7 illustrates the guide cross section and engagement during the early stages of tube forming.

FIG. 8 illustrates the guide cross section and engagement during the later stages of forming.

FIG. 9 shows a cross section of the guide means adjustment mechanism along the line A--A in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and especially to FIG. 1, there is illustrated in the form of a flow diagram an apparatus for forming a strip of material into a tube. After the strip has been fonned into a tube, the strip edges are joined by any conventional technique as, for example, high frequency welding. A flow diagram has been selected to describe the apparatus in which the invention is incorporated. The elements depicted therein are all conventional and well known in the art.

The apparatus preferably comprises a supply of strip material, a forming mill section for forming the strip material into an open tube comprising forming stands 1 through 7, a joining section for joining the edges of the open tube together and a tube shaping or sizing section comprising shaping or sizing stands 8, 9 and 10. After the strip has proceeded through the forming mill section and the tube shaping or sizing section, it is then cut to length, coiled and/or further processed as desired.

As aforenoted, the forming mill section and tube shaping section comprise forming stands which are generally conventional roll type forming stands, although dies or any other conventional forming means could be employed. The invention will hereinafter be described with reference to the use of roll forming stands although this is not meant to be limitive of the invention. Further, the number of forming stands in the forming section and shaping or sizing section is not critical and may be varied as desired.

Initial roll forming stands 1 through 4 break down the strip into a fairly open tube T as shown in FIG. 2 at 1 through 4. As shown in FIG. 2, the strip does not obtain a substantially tubular shape until it has proceeded through roll stand 4. The break down rolls may be of edge break or center break or true radius design as desired.

The forming stands 5, 6 and 7 are generally referred to as fmning roll stands since the roll which engages the open portion of the tube contains a fin for shaping and squaring up the edges of the open tube T. Typical cross sections of the open tube T at forming stands 5, 6 and 7 are shown in FIG2at5,6and 7.

After the open tube T leaves thelast forming stand, it proceeds to the joining section where the tube edges 11 and 12 are pressed together and joined in a conventional manner. The tube cross section 7 shown in FIG. 2 which is formed at the last forming stand is that of a flat oval which is preferred in accordance with this invention when joining is by means of high frequency welding techniques. However, the tube leaving the last forming-stand may have any desired cross section as are known in the art.

When the strip of material comprises a metal such as steel, aluminum, aluminum alloys, copper or copper base alloys, the preferred method of joining is by high frequency welding techniques as are known in the art from US. Pat. No. 3,037,l05, granted May 29, 1962. This invention is preferably applicable to metals, particularly those just described and most preferably to copper and copper base alloys though it may be applied to any desired strip material which is to be formed into tubing.

To illustrate the preferred method of joining the edges of metal tube, namely, high frequency welding, FIG. 3 shows a typical prior art apparatus which would comprise the joining section of the apparatus of FIG. 1.

The apparatus 10 is adapted to weld together the opposed edges 11 and 12 which form the longitudinal gap 13 in the open metal tubing T.

The open tube T is formed in the forming mill section of the apparatus of FIG. 1 and is situated in line immediately preceding the apparatus 10. The roll stands of the forming mill are generally power driven and, therefore, provide means for rapidly and longitudinally advancing the tubing T.

Weld rolls 14 comprise a pair of pressure rollers of known form which engage opposite sides of the tube T and cause the longitudinally extending gap 13 therein to become closed substantially at a weld point 15 forming a V-shaped gap 16. As the open tubing T advances to the weld point 15, the edges 11 and 12 at the gap 16 become welded together along the weld seam 17.

The coil 18 is electrically connected to a source of high frequency current, not shown. Alternatively, contacts as are know in the art may be used in place of the coil 10. The high frequency current is normally at least 10 kilocycles per second or higher. The coil 18 is also connected to a source of cooling medium (not shown) which flows through the coil tubing to keep it from overheating. The current induced in the tube edges 11 and 12 by the coil supplies the heat energy for welding.

The apparatus 10 may also include the following elements as shown in FIG. 2. An impeder 19 may be included to improve the efficiency of the induction coil 18 by increasing the impedance of the high frequency current paths around the back of the open tube T. This reduces the flow of current around the back of the tube T and increases the flow of current along the tube edges 11 and 12 running from a point on the tube edge 11 adjacent the coil 18 to the weld point 15 and back the opposing tube edge 12 to a point adjacent the coil 18. This results in more efficient heating of the edges 11 and 12 of the open tube T, the edges being heated up to the welding temperature upon reaching the weld point 15.

The impeder 19 may be of any suitably known construction and comprises a shroud 20 connected to a hollow supporting arm 21 as shown extending down through the gap 13. The actual shape of the shroud 20 shown in FIG. 1 is merely schematic and it may have any suitable shape.

A source of cooling medium (not shown) such as water is connected to the hollow supporting arm 21 for flowing water into the shroud 20 and about a core of magnetic material 22 which is held therein. The magnetic material in the core should be of an insulating nature to provide a core substantially free of eddy current losses. The core is preferably a sintered magnetic oxide insulating material, preferably of types now well known which have a low loss factor and high volume resistivity. A suitable material is marketed under the name Ferramic by General Ceramic and Steatite Corporation, the permeability thereof being substantially greater than unity. The cooling medium which passes through the hollow supporting arm 21 flows within the shroud 20 and about the Ferramic core 22 to cool the core and is generally discharged within the welded tube through holes 23.

Since the angle of the V-shaped gap 16 is important, a seam guide means 25 is generally included at a point in advance of the induction coil 18 to accurately space apart the edges of the tube T and, thereby, obtain the desired angle. The seam guide means may be formed of any suitable insulating material protruding down into the gap so that the roll stand preceding that position (not shown) will cause the tube gap edges 11 and 12 to be pressed against the opposite sides of the seam guide 25 whereby the edges are maintained with a uniform separation.

Following the joining of the tube edges 11 and 12, the tube T proceeds to the tube shaping or sizing section comprising stands 8, 9 and 10. In this section the tube can be formed into a tube having a circular cross section or any other cross section as may be desired. Thereafter, the tubing is cut to length, coiled and/or further processed by techniques well known in the art.

The instant invention has its particular application in the forming mill section of the tube forming apparatus. FIG. 4 shows a top view of a portion of the forming mill section of FIG. 1. The forming mill portion shown encompasses forrning stands 5 and 6. As shown therein, each forming stand comprises a top roll 30 and a bottom roll (not shown) disposed directly below the top roll. Each roll has a shaft 31 extending out from the roll supports 32 for connection to a power source for rotating the rolls 30 and thereby advancing the tube T. The upper roll 30 in the forming stands 5 and 6 has a fin portion 33 which is slightly raised as shown and which serves to shape and square up the edges 11 and 12 of the tubing T. The bottom roll (not shown) has a shape similar to the upper roll 30 without raised fin portion 33. The roll designs and forming stand configuration are strictly conventional and-do not form a part of the instant invention.

Between each forming stand 1 through 7 in the forming mill section in accordance with the prior art, a pair of side enclosure rolls 40 as shown in FIG. 4 is employed to maintain the tube shape between roll stands. When the strip thickness to tube diameter ratio is greater than 3 percent, the side enclosure rolls 40 adequately perform their function. However, when the ratio is less than 3 percent, pop out and/or buckling of the strip edges 11 and 12 tends to occur as shown in FIG. 4 at 41.

As aforenoted, the pop out and/or buckling is the result of the progressive accumulation of elongation in the edges 11 and 12 of the open tube T as it travels from one roll stand to the next. To eliminate this problem in accordance with the instant invention, guides 50 have been devised which extend over a substantial portion of the distance intermediate each of the forming stands 1 through 7 respectively as shown in FIG. 5.

The guides as shown in FIG. 6 have a face 51 which contacts a side surface of the tube T. The face 51 is contoured to contact and support the tube T between each of the respective forming stands 1 through 7.

The guides are adjustable and support the edges 11 and 12 in a continuous transition from both the upstream and downstream forming stands 1 through 7 as shown in FIG. 6. The contour of the face 51 which contacts the open tube T is substantially matched with the contour of the outer surface 52 of the tube T between the forming stands 1 through 7.

During the initial forming stages as between forming stands 1 and 2, 2 and 3, and 3 and 4, the guides 50 have a cross section similar to that shown in FIG. 7 which is the cross section at a point close to forming stand 1. As shown, the guides 50 contact a portion of the surface 52. of the tube T from a point near the strip edges 11 and 12 and are preferably disposed toward the bottom of the tube.

During the later stages of forming as shown in FIG. 8 as between forming stands 4 and 5, 5 and 6, and 6 and 7, the guides 50 again contact the tube T from a point near the strip edges 11 and 12 and are preferably disposed toward the top of the tube T.

' The guides 50 then generally comprise a member for supporting the tube T between forming stands 1 through 7. One face 51 of the member is generally concave and conforms to the transitional shape of the outer surface of the open tube T as it extends between forming stands. The guides 50 contact the tube T from a point adjacent the strip edges 11 and 12 and over a sufficient area to keep the strip from popping out or buckling. Generally, each guide 50 contacts at least percent of the circumferential surface 52 of the tube T for the length of the guide.

The guide 50 may be made of any desired material; plastic, metal, ceramic, etc., which will perform the desired function. Preferably, because it is desirable to avoid scratching the strip surface, plastics are employed, such as nylon or Teflon. Where plastics are employed, such as nylon, they may have sufiicient strength to be used without additional support except for mounting in the apparatus 60 of FIG. 5 or additional support such as angle irons 53, as shown in FIG. 8, may be employed to provide added stiffness and ease in attachment to the apparatus 60.

Referring again to the guide apparatus 60 shown in FIG. 5, the guides 50 are preferably held in place by affixing them by conventional means to a plate 61 which is pivotable about a spindle 62. The pivoting action is obtained by adjusting the screws 63 in opposite directions. When the desired position has been obtained, the guides 50 may be locked in position by tightening the nut 64 about the spindle 62. The pivoting assembly is preferably mounted on the conventional movable bed 65 employed when using side enclosure rolls 40. Therefore, the pivoting assembly P on either side of the tube T" can be moved toward the tube or away from the tube by means of crank 66 which is connected to a conventional screwdrive mechanism (not shown) for synchronously moving the pivoting assemblies on either side of the tube T into and out of contact with the tube.

As shown in FIG. 9, the plate 61 to which the guide 50 is affixed contains two elongated slots 67 through which bolts 68 extend into the guide 50. These bolts 68 are used to affix the guide 50 to the plate 61. By virtue of the slots 67 in the plate 61, it is possible to move the guides 50 up or down, away from or closer to the longitudinal axis of the tube or tilt them with respect to the longitudinal axis of the tube. FIG. 9 also shows the movable bed which rides within channel 69 which is affixed to the forming mill bed 70. The screwdrive 71 is also shown.

Therefore, in accordance with this invention, means are preferably provided for aligning the guides with open tube T surfaces 52 so as to obtain the desired contact between the operative face 51 of the guide and the tube surfaces. This alignment means generally comprises means 65 for moving the guides in and out of contact with the open tube; means P for pivoting the guide about an axis perpendicular to the longitudinal axis of the tubing; means 67 for moving the guide away from or closer to the longitudinal axis of the tubing; and means 67 for tilting the guide with respect to the longitudinal axis of the tubing.

While the guides have been described with reference to a member having a concave face which contacts a portion of the surface of the open tube, it is merely essential in accordance with this invention that some form of contact between a guide means be maintained over a substantial portion of the distince between forming stands. The guide means shown in the drawings comprise the preferred embodiment of this invention and numerous other approaches could be thought of including the use of a plurality of rollers or other similar technique. v

The invention is preferably applicable to non-ferrous alloys and most preferably to copper or copper base alloys.

It is to be understood that this invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are suitable of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.

What is claimed is:

1. In an apparatus for forming a tube from a strip material wherein the strip thickness to tube diameter ratio is less than 3 percent, said apparatus comprising:

forming means for forming said strip material into an open tube, said open tube having a longitudinally extending gap defined by the opposed edges of said open tube, said forming means comprising a plurality of forming stands; and

means for joining the opposed edges of said open tube;

the improvement wherein intermediate each of said forming stands, guide means are provided for preventing the opposed edges of said open tube from popping out or buckling, said guide means contacting a side surface of said open tube over a substantial portion of the distance between each of said forming stands.

2. In an apparatus as in claim 1, the improvement wherein said guide means comprises two members in opposing relationship with each member having a concave face, which contacts said open tube.

3. In an apparatus as in claim 2, the improvement wherein said concave face is contoured to contact and support said open tube between each of the respective forming stands.

4. In an apparatus as in claim 3, the improvement wherein the contour of said face conforms in a continuous transition from both the upstream and downstream forming stands to the contour of the outer surface of the tube between the respective forming stands.

5. In an apparatus as in claim 4, the improvement wherein means are provided for aligning said guide means with said tube surface. 7 v

6. In an apparatus as in claim 5, the improvement wherein said aligning means comprises means for moving said guides in and out of contact with said tube surface; means for pivoting said guides about an axis perpendicular to the longitudinal axis of said tubing; means for moving said guides away from or closer to the longitudinal axis of said tubing; and means for tilting said guides with respect to the longitudinal axis of said tubing.

7. In an apparatus as in claim 6, the improvement wherein said forming stands comprise roll forming stands.

8. In an apparatus as in claim 7, the improvement wherein said joining means comprises means for welding said edges together by high frequency induction welding.

9. In an apparatus as in claim 8, the improvement wherein said strip material comprises a non-ferrous alloy.

10. In an apparatus as in claim 9, the improvement wherein said guides are formed of a material selected from the group consisting of metals, plastics or ceram- 11. In an apparatus as in claim 10, the improvement wherein said guides are formed of nylon.

12. In an apparatus as in claim 11, the improvement wherein said guide member is affixed to a supporting .member for stiffening said guide.

13. In an apparatus as in claim 12, the improvement wherein said face of each of said guides contacts at least 20 percent of the circumferential surface of said open tube over a length of a guide. 

1. In an apparatus for forming a tube from a strip material wherein the strip thickness to tube diameter ratio is less than 3 percent, said apparatus comprising: forming means for forming said strip material into an open tube, said open tube having a longitudinally extending gap defined by the opposed edges of said open tube, said forming means comprising a plurality of forming stands; and means for joining the opposed edges of said open tube; the improvement wherein intermediate each of said forming stands, guide means are provided for preventing the opposed edges of said open tube from popping out or buckling, said guide means contacting a side surface of said open tube over a substantial portion of the distance between each of said forming stands.
 2. In an apparatus as in claim 1, the improvement wherein said guide means comprises two members in opposing relationship with each member having a concave face, which contacts said open tube.
 3. In an apparatus as in claim 2, the improvement wherein said concave face is contoured to contact and support said open tube between each of the respective forming stands.
 4. In an apparatus as in claim 3, the improvement wherein the contour of said face conforms in a continuous transition from both the upstream and downstream forming stands to the contour of the outer surface of the tube between the respective forming stands.
 5. In an apparatus as in claim 4, the improvement wherein means are provided for aligning said guide means with said tube surface.
 6. In an apparatus as in claim 5, the improvement wherein said aligning means comprises means for moving said guides in and out of contact with said tube surface; means for pivoting said guides about an axis perpendicular to the longitudinal axis of said tubing; means for moving said guides away from or closer to the longitudinal axis of said tubing; and means for tilting said guides with respect to the longitudinal axis of said tubing.
 7. In an apparatus as in claim 6, the improvement wherein said forming stands comprise roll forming stands.
 8. In an apparatus as in claim 7, the improvement wherein said joining means comprises means for welding said edges together by high frequency induction welding.
 9. In an apparatus as in claim 8, the improvement wherein said strip material comprises a non-ferrous alloy.
 10. In an apparatus as in claim 9, the improvement wherein said guides are formed of a material selected from the group consisting of metals, plastics or ceramics.
 11. In an apparatus as in claim 10, the improvement wherein said guides are formed of nylon.
 12. In an apparatus as in claim 11, the improvement wherein said guide member is affixed to a supporting member for stiffening said guide.
 13. In an apparatus as in claim 12, the improvement wherein said face of each of said guides contacts at least 20 percent of the circumferential surface of said open tube over a length of a guide. 